JPS60194695A - Pal and secam signal regenerating device - Google Patents

Abstract

PURPOSE:To reduce the cost by using only one inexpensive delay line for a luminance signal although two delay lines are used before. CONSTITUTION:For the SECAM system, a PAL modulator 6 obtains a pseudo PAL signal, which is supplied to a terminal B of a changeover switch 21 through a filter 20 which has no delay time at the PAL subcarrier frequency of a trap, etc., for attenuating a higher harmonic twice as high as a PAL subcarrier, and for the PAL system, the signal is supplied to PALBPF8 firstly to obtain a PAL carrier chrominance signal, which is supplied to a terminal A of the change-over switch 21; and one signal is selected by the switch 21 and supplied to a trailing processing circuit. Both composite video signals, on the other hand, are passed through a chrominance subcarrier trap 2 and a luminance signal delay line 3 to obtain a luminance signals. Then, the delay time relation among a bell filter 4, BPF8, and delay line 3 is set properly to manage with only one delay line for luminance signals.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention is applicable to PAL/SECA used in color television receivers capable of receiving both PAL and SKCAM images.
This invention relates to an M signal reproducing device.

Conventional configuration and problems thereof A conventional PAL-8ECAM color signal reproducing circuit is shown in FIG. The configuration of the conventional example will be explained using FIG.

The operation of the circuit block will be described in the case where all SECAM-based composite video signals have been input. From the composite video signal, only the carrier color signal is extracted by a bell filter 4. The SRCAM carrier color signal that has passed through the Bell filter 4 is subjected to FM detection by an S[AM demodulator 6, and RY and BY color difference outputs are alternately obtained for each scanning line.

Next, in the PAL modulator 6, the PAL subcarrier oscillator 16
The output from the PAL signal is used to modulate a pseudo PAL signal. Hereinafter, this will be referred to as a pseudo PAL signal.

In this case, the output is also R-Y and B-Y for each scanning line.

It is modulated alternately. During SECAM, the switch 7 is shifted to the terminal B side, so the pseudo PAL signal is guided to the PAL band pass filter 8, and after being amplified by the ACC amplifier 9, one output is sent to the switch 11 and the other is sent to the switch 11. 1
The signal is guided to the switch 12 via the H delay line 10f after being delayed by one scanning line time. Switches 11 and 12 are S
During ECAM, the output of the Ace amplifier 9 and the output of the 1H delay line 1o are switched to the SECA side because they fall to the terminal B side.
M permutator 1 day led. This SKCAM permutator 1 day uses the output of the AGO amplifier 9 and the output of the 1H delay line 1o because the pseudo PAL signal output is alternately outputted with the R-Y and B-Y signals for each scanning line. It serves to create continuous RY and BY signals. Continuous R-Y and B-Y signals are obtained from the SRCAM permutator 1 data, and are guided to a PALR-Y demodulator 17 and a PAL B-Y demodulator 18, where the R-Y signal and B-Y signal are A demodulated output is obtained and output. In addition, the G-Y demodulation output is the G-Y matrix 1
9.

Further, after the luminance signal has completely passed through the delay line 1, only the color subcarrier is attenuated by the color subcarrier trap 2, and further guided to the delay line 3, whose output becomes the luminance signal output.

Next, the entire operation of each circuit block when a PAL composite video signal is input will be explained.

The composite video signal that has passed through the delay line 1 is guided to the switch 7 as a color signal path, and to the color subcarrier trap 2 as a luminance signal path.

Now, since the switch 7 is shifted to the terminal A side, the color signal is guided to the PAL bandpass filter 8, and then to the Ace
One of the outputs is connected to the PAL matrix circuit 13 since the switch 11 is slanted toward the terminal A side.
After passing through the 1H delay line 10, the other signal is led to the PAL matrix circuit 13 via the switch 12 which is angled toward the terminal A side. This PAL matrix circuit 1
3, the output of the ACC amplifier 9 and the output of the 1H delay line 10 create the R-Y and B-Y signals, and the output of the PAL matrix circuit 13 is the R-Y signal.
The B-Y signal is sent to the ALR-Y demodulator 17 as PALB-Y.
and R-Y, respectively, to demodulator 18.

A demodulated output of B-Y is obtained. Also, the G-Y demodulation output is G
-Y matrix 19 is obtained.

(1) The output of the PAL box circuit 13 is led to the color synchronization circuit 15, where the phase of the color subcarrier on the transmitting side and the subcarrier oscillator 16 are matched.

Furthermore, after passing through the color subcarrier trap 2, the luminance signal passes through a delay line 3 and is output as a luminance signal output.

Now, the conventional PAL-1 shown in Fig. 1! :The CAM color signal reproducing circuit uses two delay lines, delay line 1 and delay line 30, to delay the luminance signal. The reason for this is explained below. Figure 3 shows SR in the conventional circuit.
The delay time relationship of CAM signals is shown. Since the SKCjAM color signal passes through the Bell filter 4, it is delayed by a time Ts. Furthermore, it is delayed by one time in order to pass through the PAL bandpass filter 8 as a pseudo PAL signal. Therefore, in order to match the delay times of the luminance signal and the color difference signal, the Bell filter 4 inserts a delay line 1 corresponding to the delay numerator s of the color signal into the luminance signal path. The delay time T, J of this delay line 1
T. -Ts (delay time in Bell filter 4). Furthermore, S in the PAL bandpass filter 8
A delay line 3 corresponding to the delay time Tp of the RCAM carrier color signal is inserted into the luminance signal path.

The delay time 'rdil-i'rd of this delay line 3
= Tp (delay time at bandpass filter 8).

FIG. 4 shows the delay time relationship of PAL signals in the conventional circuit. In the case of a PAL signal, the PAL color signal passes through the PAL bandpass filter 8 and is delayed by a time Tp. In order to match the delay times of the color signal and the luminance signal, a delay line 3 is inserted in the luminance signal path. This delay time Td is Td=Tp. Here, S at SHGAM
The ECAM color signal is filtered by a bell filter 4. In order to pass through the PAL bandpass filter 8, delay lines 1 and 3 corresponding to the delay times of these two filters are inserted into the luminance signal path. However, in the case of a PAL signal, since the chrominance signal passes only through the PAL bandpass filter 8, only the delay line 3 is required in the luminance signal path. For this reason, in PAL, the delay line 1 must delay both the color signal and the luminance signal.

As mentioned above, in the conventional PAL-8ECAM color signal reproducing circuit shown in FIG.
The number of parts will increase as the number of parts will have to be increased. Furthermore, since the delay line requires a sufficiently wide band to delay both the chrominance signal and the luminance signal, there is the disadvantage that the cost is high.

OBJECTS OF THE INVENTION It is an object of the present invention to eliminate the above-mentioned drawbacks and configure a PAL-3 EGAM color signal reproduction circuit with a small number of parts and a low-cost delay line.

Structure of the Invention The PAL-8RCAM signal reproducing device according to the present invention is a
A bell filter, SRCAM demodulator,
A pseudo PAL signal is obtained from the output of a PAL modulator, and this pseudo PAL signal is passed through a filter that does not cause a delay time at the PAL subcarrier frequency, such as a trap that attenuates twice the harmonic of the PAL subcarrier. , or directly as one input signal to a selection switching means consisting of a selection switch, etc. For PAL signals, the PAL composite video signal is first supplied to a PAL bandpass filter and its output terminal is pPAL. Obtain the carrier color signal,
This PAL carrier color signal is supplied as the other input signal to the selection switching means, and the selection switching means selects and takes out one of the signals and supplies it to the next stage processing circuit, while the luminance signal is After attenuating the color subcarrier component of both the PAL or SECAM composite video signal using a color subcarrier trap or the like, a luminance signal is obtained from the output end of the luminance signal delay line, and the luminance signal is obtained by connecting the above-mentioned bell filter, PAL bandpass filter, and luminance signal. By setting the relationship between the delay times of the delay lines in consideration of the band characteristics of each filter, only one inexpensive delay line for luminance signals is required, reducing the number of parts and costs. is measured.

DESCRIPTION OF EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. 2, 5, and 6. In FIG. 2, blocks having the same functions as those in FIG. 1 are given the same numbers and detailed explanations will be omitted.

The difference in Figure 2 from Figure 1 is that SECAM
At the output end of the PAL modulator 6 that creates a pseudo PAL signal from the signal, there is a filter 20 such as a trap that attenuates harmonics twice the PAL subcarrier frequency (there is no delay time at the subcarrier frequency of the pseudo PAL signal). , and switch 21 to switch the pseudo PAL signal through this filter 2o.
One input of is supplied to terminal B, and on the other hand,
Regarding the PAL signal, the composite video signal 1 is directly supplied to the PAL bandpass filter 8 from the input terminal 1N, and this PAL signal is
The PAL carrier color signal output from the AL bandpass filter 8 is supplied to the terminal A as the other input of the changeover switch 21. On the other hand, regarding the luminance signal, the composite video signal is first guided to a color subcarrier trap 2 to attenuate the color subcarrier component, and then guided to a delay line 3, from which a luminance signal output is obtained.

Next, the operation of the embodiment will be explained based on FIG. First, the case where an SRCAM composite video signal is input will be described. The SRCAM composite video signal is input to the Bell filter 4 and converted into only color signals, and then the SECAM demodulator 6 converts the F
M-detection is performed to obtain R-Y and B-Y color difference outputs alternately for each scanning line, and this color difference output is guided to the PAL modulator 6, and the PAL
The output of the subcarrier oscillator 16 is used to modulate a pseudo PAL signal to obtain a pseudo PAL output. Thereafter, the pseudo PAL signal is guided to a filter 2o, such as a trap, which attenuates harmonics twice the PAL subcarrier frequency, which have no delay time at the subcarrier frequency of the pseudo PAL signal.

This filter 20 may be omitted in some cases. The pseudo PAL signal that has passed through the filter 20' (H) is guided to the switch 21 as one input.

Since switch 21 is connected to terminal B during SKCAM, the output of filter 20 is connected to terminal A via switch 21.
Connected to GO amplifier 9.

Here, since both switches 11 and 12 are connected to terminal B during SECAM, the output of AGO amplifier 9 is output from switch 1.
1 through SECAM permutator 1 day, also Ac
The output of the e amplifier 9 is connected to the SICCAM Hermudata 14 via a 1H delay line 1o and a switch 12. This SRCAM permutator 1D converts the pseudo PAL signal sent line-sequentially into a continuous R-Y signal and B-Y signal using the output of the ACC amplifier 9 and the output of the 1H delay line 10, The output 1 is led to a PALR-Y demodulator 17 and a PALB-Y demodulator 18 to obtain demodulated outputs of RY and BY. A G-Y demodulated output is produced by a G-Y matrix 19.

On the other hand, the SICCAM composite video signal is supplied to a color subcarrier trap 2, and after attenuating the color subcarrier, is supplied to a delay line 3. If the time for which the SICCAM color signal is delayed by the bell filter 4 is Ts, and the delay time eTa of this delay line 3 is taken, then Td=Ts may be satisfied. This situation is shown in FIG.

Next, the operation of each circuit block when a PAL composite video signal is input will be explained. PAL composite video signal hap A
The signal is input to the L-band pass filter 8 and becomes only the color signal, which is then supplied to the switch 21.

During PAL, the switch 21il+ is shifted to the terminal A side, so the output of the PAL bandpass filter 8 is AC
C amplifier 9. Here, both switches 11 and 12 are connected to terminal A during PAL, so the ACC amplifier 9
The output of PAL matrix 1 is transmitted through switch 11.
3, the output td of the ACC amplifier 9 is connected to the PAL matrix 13 via a 1H delay line IQ and a switch 12.

In this PAL matrix 13, the output of the Ace amplifier 9 and the output of the 1H delay line 1o are used, and the power of both rivers is subtracted. B -Y signals are created by adding the llR-Y signals, and the outputs thereof are led to the PALR-Y demodulator 17 and PAL B-Y demodulator 18, respectively, to obtain the demodulated outputs of R-Y and B-Y. . G-
The Y demodulated output is produced by the G-Y matrix 19.

On the other hand, the PAL composite video signal is supplied to the color subcarrier trap 2, and after attenuating the color subcarrier, the delay line 3
supplied to Time Tp for which the PAL color signal is delayed by the PAL bandpass filter 8.

If the delay time of this delay line 3 is Td, then Td
= Tp. This situation is shown in FIG.

From the above, in order to use only one delay line 3 for the luminance signal even in PAL'SECAM, the delay time Ts of the bell filter 4, the delay time Tp of the PAL bandpass filter 8, and the delay time of the delay line 3 are required. The relationship between Td may be such that Td = Tp = Ts.

In addition, since the Bell filter 4 generally has a narrower band than the PAL bandpass filter 8, the delay time Ts in the Bell filter 4 (!: P A L between the delay time Tp in the Hunthas filter 8) There is a relationship Tp(Ts. Therefore, between Td, Tp, and T5, Tp<T
If the relationship a<Ts is established, the time difference between the color signal output and the luminance signal output on the screen will not be noticeable in both PAL-8 ICCAM systems, and only one delay line is required for the luminance signal path. .

Further, in FIG. 2, the output of the PAL modulator 6 does not pass through the PAL bandpass filter 8, but this does not pose a practical problem since the output of the PAL modulator 6 is only a carrier color signal.

Effects of the Invention As described above, according to the present invention, the conventional PAL/SEC
While the AM color signal reproducing circuit uses two delay lines, a wideband delay line that delays the composite video signal and a luminance signal delay line, the PAL and SRCAM color signal reproducing circuit of the present invention uses an inexpensive delay line. The delay line for the luminance signal can be reduced to one, which is effective in reducing the number of parts and cost.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a conventional PAL and SECAM color signal reproducing circuit, and FIG. 2 is a PAL in an embodiment of the present invention.
, a block diagram of a SICCAM signal reproducing device, FIG. 3 is a diagram showing the delay time relationship of SECAM signals in the conventional circuit, FIG. 4 is a diagram showing the delay time relationship of PAL signals in the conventional circuit, and FIG. The figure shows the delay time relationship of SRCAM signals in the present invention, and FIG. 6 shows the delay time relationship of PAL signals in the present invention. 0 2...Color printing carrier wave trap, 3... ...Delay line, 4...Bell filter, 6...
°SECAM demodulator, 6...PAL modulator, 8
...PAL band pass filter, 20...
...Filter, 21...Selection switching means. Name of agent: Patent attorney Toshio Nakao and one other person
RQQ or Vessel

Claims (3)

[Claims] (1) An input terminal for inputting a composite color television signal;
The composite color television signal is connected to this input terminal and inserted at the transmitting side of the SECAM signal transmission system, and has the opposite characteristics to the Pel filter that attenuates the carrier color signal.
In the case of an AM system, a first filter means for extracting a carrier color signal from a composite color television signal, and an SRC connected to an output end of the first filter means for FM demodulating the carrier color signal.
AM demodulation means and output signal 1 of the SRCAM demodulation means
a converting or modulating means for converting or modulating into a PAL system or a signal similar to it; a second filter means for removing harmonic components included in the output signal of the converting or modulating means as necessary; and the converting or modulating means. selection switching means for inputting the output signal of the means or the output signal of the second filter means as a first input signal; and a selection switching means connected to the composite color television signal input terminal, the selection switching means is connected to the composite color television signal input terminal and delays the luminance signal by a time Td. and third filter means connected to the composite color television signal input terminal for extracting the carrier color signal, the output signal of the third filter means being connected to the second filter of the selection switching means. A PAL-8 ICCAM signal reproducing apparatus, characterized in that the first input signal or the second input signal is supplied as an input signal and is selectively outputted from the output of the selection switching means. (2) The PAL-8ECAM signal reproducing apparatus according to claim 1, wherein the delay time Tdi of the delay means is approximately equal to the delay time Tp of the third filter means. (3) Claim 1, which is characterized in that the delay time Td of the delay means, the delay time Ts of the first filter means, and the delay time of the third filter means Tp < Td < Ts. PAL-8RCAM signal reproducing device as described in 2.